Jason Day is bracing himself for one of the PGA Tour's toughest golf courses after posting a solid opening round in his Farmers Insurance Open title defence in California.
Day, a two-time champion at the Torrey Pines event, says his five-under-par 67 on the North course has him in a good position – five shots back of first-round leader Jon Rahm (62).
Day's playing partner Rahm, the 2017 winner, missed a birdie putt on his last hole to tie the North course record but seven birdies, two eagles and a bogey gave the Spanish World No.7 a 62.
Rahm holds a one-shot lead over Doug Ghim and World No.1 Justin Rose, who each posted 63 on the North course.
Three-time major winner Jordan Spieth is a further two shots back at seven under having posted a solid 65.
Day and Rahm now face the brutal South course at Torrey Pines, which hosted the 2008 US Open and was last year ranked the eighth-hardest course on the PGA Tour – averaging almost a stroke over its par of 72.
"We've got the big boy course tomorrow so that should be fun," Day joked after his round.
"I have to keep chipping away because Rahm played some tremendous golf today.
"But I love tough golf courses so if I can hit a few more fairways I know I can get myself up that leaderboard."
Day and Matt Jones (67) finished day one as leading Australians, with World No.16 Marc Leishman (68) and John Senden (68) a shot back at four under.
Tiger Woods and Adam Scott are well positioned after each signing for a 70 on the South course to earn a two-under total .
However, Woods, whose eight wins at Torrey Pines include the 2008 US Open, said he would need to go low on the North on Friday to stay in contention in his first PGA Tour event of the year.
"Shooting a couple under par on the South is not so bad but now I'm forced to have to shoot a low one tomorrow just like most of the field did there today," Woods said.
"I've got a competitive round under my belt," said Woods of his first PGA Tour round since winning the Tour Championship in September.
"As I get more comfortable (this week), I'll fire at more flags, be a little bit more aggressive and start feeling more comfortable being back competing."
One shot back of Scott is fellow Queenslander Cameron Smith, who posted a 71 to sit at one under and one shot ahead of Australian Cameron Davis (72).
Rod Pampling rounds out the Australian contingent in the 156-player field and is three over after a 75.